The present invention relates to a canister for storing dry powered goods in general. More specifically to a canister with a lid that incorporates a vacuum relief valve for relieving negative pressure within the canister when opening, precluding dispersing a portion of the uppermost contents away from the canister during lid removal.
Previously, many types of sealed lids have been used in endeavoring to provide an effective means to seal the contents within a storage vessel. In most cases a lid is used that contains a seal effectively sealing and securing the container, however, no provision has been included to prevent dispersing powdered contents away from the container during lid removal.
A search of the prior art did not disclose any patents that possess any of the novelty of the instant invention, however the following U.S. patents are considered related:
Letsch et al. in U.S. Pat. No. 4,754,888 discloses a carafe with an inner container surrounded by a casing. The inner container and the casing have an opening at the top which may be closed by a separate plug. The plug and opening in the container and casing are shaped such that it is possible to fill or empty the inner container while the plug is still in the opening. The plug and container both have mating grooves that provide opposed flow paths into and out of the container. The container also includes a basin around the top for receiving coffee from a coffee maker and the plug has openings to provide a flow path from the basin into the container interior.
Karp in U.S. Pat. No. 5,249,703 teaches a travel mug that includes a container and a lid in combination. The container has a handle and an annular lip that has an annulus capable of forming a seal with the top side of the annular lip. A cylindrical well in the lid has a vertical dividing wall such that the lid may be readily rotated by hand. The retaining arms extend from the underside of the lid and engage the underside of the annular lip to pull it into tight abutment. Diametrically opposed gaps in the lip act as passageway for the retaining arms. Similarly diametrically opposed notches in the lid align with the gaps to allow liquid to be poured from the container. A plug is used for closing the opening of the carafe that includes a lid with its lower rim serving as a seal against the bottom of the basin when it is screwed into the opening.
U.S. Pat. No. 5,918,761 issued to Wissinger is for an insulated container and cover combination that has an outer container shell terminating at an opening with a surrounding edge. An inner container shell is nested within the outer container shell and has an opening surrounded by a continuous edges in abutment with the surrounding edge. The inner container shell is spaced inwardly and is out of contact with the outer shell. A cover mounting assembly is attached to the outer shell adjacent to the opening. A single seal, made of elastomeric material, has a sealing surface disposed at the interface of the shells. Locating rings define the removable cover mounting assembly and locate the single sealing ring on the inner and outer shells.
For background purposes and as indicative of the art to which the invention is related reference may be made to the remaining cited design patents.
There are a myriad of different types of jars, containers, jugs, bottles, cans, and canisters used for storing various articles such as foodstuffs and the like. In order to provide some semblance of protection, most storage containers have some type of lid for closure and for protection of the contents from exposure to the environment. Particularly relevant to food, the container must be sealed, preferably incorporating an air tight seal which is the most desirable for prolonging the useful life of the contents. In order to secure the container sufficiently a seal is normally used which, if long term storage is required, may be a permanent lid that must be opened by piercing the top and removing the material such as in a metal can. Further bottles and jars are sealed by the use of a threaded lid with a resilient seal between the lid and the body that is compressed when installed.
Canisters have a different problem in that the material inside must be sealed to prevent atmospheric contamination but must be readily available to be used without special tools or prolonged twisting of lids or the like. Some canisters use compression latches and hinges to provide a tight seal and still have relatively easy access to the contents. Others like ceramic jar canisters simply use a compressible seal that is held in place by the weight of the lid itself
The optimum type of closure is a simple resilient gasket that compresses very tightly when inserted into the canister creating a completely air tight seal. There is however a down side to this approach in that if the seal is sufficient to completely block out any air it also creates negative pressure when it is removed which can be detrimental if a powered food stuff is stored inside such as flour, confectioners sugar, baking powder, corn starch and the like. The result is that if the container is full and the lid is removed the vacuum created within draws some of the powered substance along with the lid and spreads it out away from the canister and onto the surrounding area making an unnecessary mess that must be cleaned up and any contaminated material disposed of
It is therefore a primary object of the invention to add a vacuum relief valve to the lid to alleviate the negative pressure when removing the lid. As the lid is pulled upward the interior area of the canister is increased creating the vacuum which can pull the contents up at the same time, however, with the relief valve in place the valve outer fringes collapse and the negative pressure is released through the vents eliminating the problem entirely.
A secondary problem is also expunged in that as the vacuum created in the removal of a lid, with a tight seal, makes this type of lid detaching difficult. The better the seal the harder it is to remove the lid and it is important to have a secure seal to make the canister air tight. It may be clearly seen that the invention solves an important task which is appreciated by the user particularly when a powered substance is stored inside that may be spilled if one has to pull hard and all of a sudden the lid comes off easily loosing control of the canister entirely.
Another object of the invention is the ease of manufacture as once the injection mold incorporates the stem and vents it is easy to manually push the valve in place by hand which takes little effort and yet grips securely. The valve adds little to the overall cost of manufacture and assembly.
These and other objects and advantages of the present invention will become apparent from the subsequent detailed description of the preferred embodiment and the appended claims taken in conjunction with the accompanying drawings.